Posted by **al** on Wednesday, January 12, 2011 at 11:34pm.

solve with substitution

5x - y=-1

15x=2y

- math -
**Haley**, Wednesday, January 12, 2011 at 11:42pm
solve the first equation for y.

5x-y=-1 subtract 5x from both sides

-y=-1-5x divide by -1

y=1+5x

now, plug this answer in for y in the second equation.

15x=2y

15x=2(1+5x)

15x=2+10x

5x=2

x=.4

plug this(x=.4) into the equation for y.

y=1+5x

y=1+5(.4)

y=1+2

y=2

therefore, x=.4 and y=2 or (.4, 2)

- math -
**al**, Thursday, January 13, 2011 at 12:37am
actually that does not work out, plug x and y into original equation...

- math -
**al**, Thursday, January 13, 2011 at 12:39am
actually that does not work out, plug x and y into original equation...

y=1+2

y=3

then it works out

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